Glycoside hydrolases are enzymes that cleave ester bonds, and many glycoside hydrolases that concurrently have a transglycosylation activity have also been reported. α-glucosidase, which can be said to be a typical glycoside hydrolase, generally has a hydrolysis activity (hydrolysis reaction) and a transglycosylation activity (condensation reaction) in combination. α-glucosidase is widely present in nature, from microorganisms to higher animals and higher plants. α-glucosidase is the most useful enzyme in industries, and is utilized for the decomposition, synthesis and the like of saccharides.
Due to advances in technology, it has become possible to vary (improve) the characteristics of enzymes. Various attempts for modification have also been made for α-glucosidase (for example, see Patent Documents 1 to 3).